1. Field of the Invention
This invention relates to optical systems and elements, and more specifically, to apparatus for changing the bit cell interval or frequency of a serial optical data packet comprising light pulses that are sequentially located in bit cells.
2. Description of the Prior Art
The art of optical systems and elements includes various devices that provide multiple optical paths.
U.S. Pat. No. 3,506,834 provides a time division multiplex optical transmission system wherein an input laser beam is sequentially deflected to a plurality of individual beam positions that form a diverging cone. A first deflector is located at the apex of this diverging cone. A first lens is located at the base of this diverging cone. This first lens accepts the individual beams, and forms them into a like plurality of parallel beams in the form of a cylinder. A modulator is provided at the location of each of these parallel beams. In this way, information is imparted to each individual parallel beam. A second lens accepts the plurality of modulated parallel beams, and operates to form a like plurality of beam positions that take the shape of a converging cone. The second lens is located at the base of this converging cone. A second deflector is located at the apex of this converging cone. The second reflector is position synchronized with the first reflector, and operates to form the plurality of beams into a single output beam. U.S. Pat. No. 3,597,047 describes a light beam deflector that provides multiple reflection and includes an electrooptic crystal whose index of refraction is controlled as a function of the magnitude of an input analog signal. When this device operates as an analog-to-digital coder, the analog signal is applied to the crystal to control its index of refraction as a function of the magnitude of the analog signal. A beam of light now enters the crystal, is refracted thereby, and then exits the crystal. Depending upon the magnitude of the analog signal, the beam is usually reflected by a mirror arrangement so as to reenter the crystal. In this way, the beam of light makes multiple passes through the crystal, the beam being refracted during each pass as a function of the magnitude of the analog signal. The beam continues to pass through the crystal until the beam has been moved to a position where, when it exits the crystal for the last time, the beam misses the mirror arrangement, and passes on to a two-dimensional planar detector array. The individual detector position at which the beam strikes the array is a function of the magnitude of the analog signal, and the output of this individual detector provides a digital indication of this analog magnitude.
U.S. Pat. No. 3,838,278 describes an optical switching network that operates to gate an optical input pulse to one of a plurality of outputs. The input pulse is first divided into a plurality of identical pulses. Each of these individual pulses is then applied to the input of one of a plurality of optical delay means (in the form of optical fibers of different lengths), each providing a different delay for its input pulse. The output of each optical delay means is associated with one of the plurality of photodetector outputs. Selection of an individual photodetector enables the original input optical pulse to appear as a delayed electrical output pulse, the magnitude of the delay being that which is associated with the selected photodetector. If the variable delay that occurs between the various outputs is undesirable, the patent states that a complementary optical delay network can be inserted prior to the plurality of photodetectors, or complementary electrical delay networks can be inserted after the photodetectors.
U.S. Pat. No. 4,090,779 describes a light beam position control system having a cube that receives a beam of light incident on one surface thereof. The beam enters the cube and reflects internally of the cube, forming a spiral path that extends down the width of the cube. The beam then emerges from a surface of the cube. The first cube surface to internally receive the beam includes a control means that operates to modify the internal reflection angle of the beam. This modifies the beam's internal spiral path, and causes the beam to emerge from the cube at a position that is controlled by operation the control means.